Before holes are bored the timbers are selected, measured, and cut. They are then laid in position, nailed
temporarily and the bore holes located. Bore hole locations are rechecked, then bored (para 2-9e)
Purlins for large roofs are continuous members which rest on the trusses. In small roof construction short
purlins are inserted between the rafters and toe nailed to them (para 2-10).
For residential construction in the U.S. studs are normally installed on 16-inch centers. In TO type
construction, studs are frequently spaced as much as 8 feet on center, in which case girts must be used to
provide stiffness to the wall and nailing bases for the siding (para 2-11b).